Rotary electromagnetic actuator



Patented Sept. 4, 1962 3,052,828 ROTARY ELECTROMAGNETIC ACTUATOR Robert B. Phinizy, Los Angeles, Calif., assignor to P.S.P. Engineering Co. Filed Aug. 5, 1959, Ser. No. 831,874 2 Claims. (Cl. 317-199) This invention relates to rotary electromagnetically operated actuators.

There are many applications wherein it is desired to have a rotative output from an electromagnetically actuated device. Such devices have been known in the prior art wherein an electromagnet having an armature or plunger with a relatively short stroke, has been arranged to provide a rotative shaft output. However, the prior art devices have generally included additional parts or What might be said to be complications utilized for the purpose of providing for only rotative and not axial movement in the shaft output; to provide for axial movement only and not rotative movement of the armature or plunger, and to provide for effective conversion and transmission of motion from the armature to the rotative output.

It is the object of this invention to provide an electromagnetic device having a rotative output of simplified, durable, and effective construction and employing a minimum number of highly reliable parts.

It is another object of the invention to provide a device as in the foregoing object wherein the motion converting and transmitting mechanism is reduced to two parts having mutual engagement, one carried by the armature or plunger and the other by the rotative output shaft.

A further object of the invention is to provide a device as in the foregoing objects wherein the motion converting and transmitting means comprises a cam carried by the output shaft and a cam follower member carried by the armature or plunger cooperating therewith and which actuates the cam for rotating the output shaft in response to linear movement of the armature of plunger.

A still further object of the invention is to provide a device as in the foregoing objects wherein the output shaft is in a position normal to the plunger of the electromagnet or the stem of the armature of the electromagnet.

Further objects and additional advantages of the invention Will become apparent from the following detailed description and annexed drawings, wherein:

FIGURE 1 is a cross-sectional elevation of a preferred form of the invention; and

FIGURE 2 is a side elevation of the invention partly in section.

Referring now more particularly to the drawings, numeral designates generally an electromagnet or solenoid assembly comprising a winding 11 of preferably cylindrical conformation. The winding 11 is within a cylindrical casing or housing 13 of magnetic material. At the one end of the winding 11, is a disc 15 of magnetic material and having a bore 16 of substantially the same diameter as the central bore or opening through the solenoid winding 11.

Numeral 17 designates an end cap or closure which may be formed of insulating or non-magnetic material which closes the end of the casing 13, fitting in an annular shoulder in the end of the casing a shown and against the plate 15.

Numeral 21 designates the core of the electromagnet or solenoid, the core closing the end of the housing 13 and having a cylindrical portion 22 which fits into the bore within the solenoid winding 11. The core 21 has a central bore 23 within which is a sleeve 24 and slidable in the sleeve is the plunger or armature stem 25. The end 26 of the plunger or stem is of smaller diameter and is attached to the armature member itself 27 which is of to the housing 31.

magnetic material to complete the magnetic circuit through the windings and the core, it being made of suitable magnetic material.

The rotative output shaft of the device is designated at 30 and is in a position normal to the plunger or armature stem 25 with the axes of the two shafts crossing as shown. The output shaft 30 is transversely disposed in a housing 31 made of insulating or non-magnetic material having a peripheral flange or shoulder 32 on one side whereby it is attached to the housing 13 by the bent-over flange 33 as shown.

The shaft 30 is mounted in needle bearings as designated at 34 in FIGURE 2 which are disposed in bores as shown at 35 in the housing 31 as shown in FIGURE 2. The needle bearings may be of conventional construction comprising elongated needle members 36 pointed at the ends and held within a bearing retainer 37 fitting in the bore 35 and engaging a retainer ring 40 fitting in an annular groove in the shaft 30. A needle bearing similar to that just described is provided at the other end of shaft 30 not shown in FIGURE 2.

The end of the plunger or armature stem 25 is formed as a yoke as shown at 42 in FIGURE 2 and pivoted between the legs of the yoke on a pivot pin 43 is a cam roller 44. The cam roller 44 engages with a cam member or actuator member 45 rigidly mounted on the shaft 30. The cam member 45 has the shape shown in FIG- URE l. The camming or actuating surface is designated at 46, the rotative output being through a limited number of degrees. It will be noted that the camming surface 46 includes a portion of greater radial distance from the center of shaft 35} extending to a portion of less radial distance, the camming surface terminating in outwardly curving portions of the cam. In operation, upon energization of the electromagnet, the armature 27 moves upwardly as shown in FIGURE 1, thus moving the plunger 25 linearly to close the air gap between the armature 27 and core 21. This movement imposes a thrust by roller 44 against the cam surface 46 which tends to rotate the cam 45 in a clockwise direction until the roller 44 moves against the outwardly extending portion of the cam surface as designated at 48. The action is a rotary movement resulting from the thrust of the plunger. A can be seen, the mechanical advantage of the cooperating parts in producing torque or rotative effort is greater at the beginning of the plunger stroke when the pull on the armature is weaker. The mechanical advantage reduces during the stroke by reason of the shape of the camming surface 46 as may be seen so that the mechanical advantage is less when the thrust, that is, the magnetic pull, is greater as the air gap closes.

Referring to FIGURE 2, numeral 50 designates a spiral torsion spring having one end, that is the inner end, attached to the shaft 30 and the other end attached When the shaft 30 is rotated in the manner described, tension or stress is placed in the spring 50 and upon release of the electromagnet, the position of the shaft 30 is restored to normal by the spring 50 and the plunger and armature 27 are returned to the position shown in FIG. 1. In the restoring motion, the cam 45 transmits motion through the cam follower 44 to the plunger. As can be seen, the motion is transmitted either from the plunger to the shaft or vice versa without lost motion and very effectively utilizing only the two mutually engaging parts, which are of extremely durable inexpensive, and long lasting construction, not in any Way liable to possible malfunction or need of maintenance. In other words, the device embodies the ultimate in simpllcrty, ruggedness, and minimum number of reliable,

and dependable parts.

The foregoing disclosure is representative of a preferred form of the invention and is to be interpreted in an illustrative rather than a limiting sense. The form of the invention disclosed is illustrative of equivalent assemblies and assemblies constituted of equivalent parts, such as may occur to and be adopted by those skilled in the art. Accordingly, it is intended that the invention shall be accorded the full scope of the claims appended hereto.

What is claimed is:

1. In an electromagnetic device having a rotary output in combination, a solenoid winding, a solenoid plunger cooperating with the winding, and arranged for axial movement, an output shaft having a position normal to the axis of the solenoid plunger, means comprising a cam on the output shaft and a cam follower carried by the solenoid plunger for transmitting motion directly between the plunger and the shaft whereby linear movement of the plunger rotates the shaft, said cam follower comprising roller means carried by the solenoid plunger, the said cam lying in a plane parallel to the plane of the said roller means and normal to the aXis of 20 hold the cam in firm contact with the roller means of the cam follower and to return the shaft to an initial position when the solenoid plunger is released, and the said cam having a cam surface rising at a rate proportional to the closing of the magnetic air gap of the electromagnet, i.e. the position of the armature relative to the electromagnet whereby compensation is provided for the variable magnetic pull of the electromagnet in the torque which is transmitted to the shaft.

2. The structure as in claim 1, wherein the said plunger comprises a yoke having the roller means of the cam follower journalled on a pin extending between the legs of the yoke.

References Cited in the file of this patent UNITED STATES PATENTS 2,124,604 Bidwell July 26, 1938 2,497,466 Olson Feb. 14, 1950 2,528,386 Napper Oct. 31, 1950 2,779,881 Lundquist Jan. 29, 1957 2,963,915 Strau b Dec. 13, 1960 

